Tower assembly for mounting a crossbar to a vehicle roof rack

ABSTRACT

A tower assembly for detachably mounting a crossbar to the rail of a vehicle roof-mounted rack. The tower assembly includes a body having a selectively operable clamping mechanism housed in the tower body and includes a wedge-shaped portion adapted to be disposed generally between the rail and the crossbar when the rail and the crossbar are received in the tower body. The clamping mechanism urges the bar and the rail away from each other and against the tower body to thereby secure the bar and the rail to the tower simultaneously.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. patent applicationSer. No. 08/587,287 filed Jan 12, 1996 and now U.S. Pat. No. 5,730,343.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates generally to vehicle roof racks, and moreparticularly, to a tower assembly for detachably mounting a crossbar toa roof rack of a vehicle. Crossbars are the structural elements of arack that extend over a portion of the roof of a vehicle to provide amount for articles such as luggage, or for article-carrying accessoriessuch as bicycle carriers, ski carriers and the like.

The primary application for the tower assembly of the present inventionis to facilitate installation of crossbars on factory-installed vehicleroof racks. The crossbars on factory racks are often too weak to carry aparticular load, or are configured incompatibly with a particularcarrier. Factory crossbars may be mounted too close to the roof of avehicle to allow the attachment of a particular carrier, or thesecurement of a particular load. Thus there is a need for easily-added,structurally-sound crossbars. Furthermore, factory crossbars are oftendifficult to remove and install. The present invention enables a personto conveniently mount a crossbar to a factory rack, with the strength,shape and relative height of the crossbar selected to match the specificload and/or carrier that is to be placed on the vehicle. The inventionmay be used to mount crossbars directly to a vehicle or to removableracks.

Conventionally, carriers are mounted directly to crossbars, using asemipermanent connection such as a U-bolt, bolted bracket or fixedsleeve. The connection between the carrier and the crossbar may make itdifficult to remove the carrier from the crossbar. Removal andre-installation of a carrier may be required, for example, to improveaesthetics or provide protection to the vehicle, or a carrier may beexchanged for a different activity, such as from skiing to biking. Asingle carrier may also be used on another vehicle.

Because of the connection between the crossbar and carrier, removal andinstallation of a carrier usually requires tools and the use of smallparts like nuts and lockwashers which are difficult to handle and whichcan be easily misplaced. If the crossbar cannot be easily removed fromthe vehicle, then removal of a carrier requires one to reach or work ontop of the vehicle. A roof can be hard to reach and difficult to see,and it may be scratched in the process of adding or removing a carrier.For all of these reasons, there is a need for a tower that is easilyadded and removed from a factory rack.

A principal object of the present invention is to overcome the problemsdiscussed above. The tower assembly of the present invention providesfor easy removal and installation of crossbars on a vehicle. In sodoing, the tower assembly allows the convenient attachment of carriersto crossbars. The risk of damage to the roof of the vehicle isdecreased, and once a carrier is attached to the crossbars, thecarrier/crossbar assembly may be readily removed from and thenreinstalled on the vehicle using the present invention. For optimumconvenience, a carrier/crossbar assembly may be preassembled for eachactivity or carried load, so that the vehicle can be quickly fitted foreach activity.

The tower assembly of the present invention may be mounted on variousdesigns and configurations of factory-installed roof racks. The towerassembly may be selectively positioned on a rail so that the spacingbetween adjacent tower assemblies can be easily set for variousvehicles. The tower assembly enables a single crossbar/carrier assemblyto be moved quickly and easily from vehicle to vehicle even if thevehicles and roof racks are different. No tools or parts interchangesare required. The tower assembly is sleek and effective, resulting in acrisp, clean-looking, secure installation on most configurations ofvehicle roof racks.

When a crossbar/carrier assembly is to be removed and stored, it isoften difficult to store the assembly with a conventional tower, becauseit projects outwardly from the crossbar, significantly increasing thesize of the resulting assembly. The tower assembly of the presentinvention is easily removed from the crossbar, so that it can be storedseparately from the crossbar/carrier assembly, further reducing storagespace. The tower assemblies described herein may be interchangeably usedwith multiple crossbar/carrier assemblies, reducing the cost to theuser.

Accordingly, it is an object of the present invention to provide a towerassembly for detachably mounting a crossbar to the rail of a vehicleroof rack. The tower assembly includes a unitary body for securing acrossbar to a rail of a roof rack. The tower assembly houses a clampingmechanism, which in turn includes first and second levers, eachconnected to the body for pivoting in opposite directions about a commonpivot axis. The clamping mechanism further includes an actuatorconsisting of a handle operable for rotatably displacing a threaded boltthrough a slider. When the bolt is rotated, the slider is pulled towardthe pivot axis and engages both the first and second levers to pivot sothat the first lever clamps the crossbar to the body and the secondlever clamps the rail to the body. The actuator is operable to releasethe clamping action of the levers so that the tower assembly may bedetached from the crossbar and rail. A resilient pad partially coversthe exposed portions of the claw to prevent marring of the rail orvehicle, increase the frictional grip of the tower on the rail orvehicle, and loosely hold the claw in an open position to make it easierto put the tower on a rail or vehicle.

The present invention also includes tower assembly for detachablymounting a transversely extending crossbar of predeterminedcross-section to a longitudinally extending rail on a vehicle-mountedroof rack. The tower assembly includes a tower body for receiving aportion of the crossbar and an adjacent transversely oriented portion ofa rail and is adapted to constrain the movement of the rail and the baraway from one another. In at least some embodiments of the presentinvention a selectively operable clamping mechanism is housed in thetower body and includes a wedge-like portion adapted to be disposedgenerally between the rail and the crossbar when the rail and thecrossbar are received in the tower body. The clamping mechanism urgesthe bar and the rail away from each other and against the tower body tothereby secure the bar and the rail to the tower simultaneously.

Additional objects and advantages of the present invention will be morereadily understood after a consideration of the drawings and thedetailed description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view showing two pairs of the tower assembly ofthe preferred embodiment installed on a vehicle roof rack, each pair oftower assemblies holding a crossbar;

FIG. 2 is a front elevation of the preferred embodiment, shown with aportion of a crossbar and factory rail clamped by the tower assembly;

FIG. 3 is a cross-sectional front view of the preferred embodiment,taken generally along line 3--3 in FIG. 8, with dashed lines showing thehandle in its operating position;

FIG. 4 is an exploded, isometric view of the preferred embodiment, withdashed lines indicating the approximate assembly of the components;

FIG. 5 is right side elevation of the preferred embodiment, with thecrossbar removed and the factory rail shown in dashed lines to revealdetails of the invention;

FIG. 6 is a right side elevation of an embodiment similar to thepreferred embodiment, but lacking a pad to cover the claw, shown with acrossbar inserted into the tower assembly;

FIG. 7 is a cross-sectional top view of the embodiment shown in FIG. 5,taken generally along line 7--7 in FIG. 5, with a portion of theclamping assembly being removed to show the details of other portions ofthe clamping mechanism;

FIG. 8 is a top plan view of the preferred embodiment, shown with thecrossbar in dashed lines to reveal details of the invention;

FIG. 9 is a bottom plan view of the preferred embodiment, as shown inFIG. 5; and

FIG. 10 is a cross-sectional bottom view of the preferred embodiment,taken generally along line 10--10 in FIG. 6.

FIG. 11 is a cross-sectional front view of an alternative embodiment ofa tower according to the present invention;

FIG. 12 is a right side elevation of the tower of FIG. 11.

FIG. 13 and 14 are a perspective views of a cam for use in theembodiment of FIGS. 11 and 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The tower assembly of the present invention, generally indicated at 10,is shown in FIG. 1 mounted on the rails R of a roof-mounted vehicle rackto support a pair of crossbars. Two pairs of the detachable towerassemblies are required, each pair supporting an associated crossbar. Asshown in FIGS. 2 and 3 and the exploded view of FIG. 4, tower assembly10 includes a unitary body 12 formed with a top 13 defining a dome-likeenclosure with a crossbar clamping surface or interior wall 14 (seeFIGS. 5 and 6) for receiving a crossbar, and a base or bottom indicatedat 30. Parallel rows of linear teeth 16, shown in FIGS. 3 and 5, areformed on interior wall 14 shaped as protruding ridges for engaging acrossbar and preventing it from rotating. As shown in FIGS. 3 and 4,body 12 includes an inclined rear wall 18 provided with an oblongaperture 20, a bolt aperture 22 and a lock aperture 24. An indented,semispherical receptacle 26 and a further recess 28 are formed in rearwall 18 for receiving an actuator handle, in a manner to be described.The bottom of body 12, shown at 30, is defined by a pair of spaced-apartlegs 32 each having an upper surface 34. As can be seen, body 12 isformed as a unit, defined by top 13, rear wall 18, bottom 30 and sides38. The unit is generally C-shaped when viewed in profile, providing anopening 36 bounded by a rail clamping surface 37 for receiving a rail ofa roof-mounted rack. As shown in FIG. 4, sides 38 include a keyhole-shaped slot 40 for receiving a pad 98.

A clamping mechanism generally indicated at 42 in FIGS. 3 and 4, ishoused in body 12 and includes a first lever or lifter 46, a secondlever 66, a cylindrical slider 84, a bolt 86 and a handle 90. Lifter 46and lever 66 are both pivotally mounted to body 12 at a common pivotaxis defined by pivot pin 44. As shown in FIGS. 5 and 6, lifter 46 isformed with a pair of parallel, spaced-apart sidewalls 48 each having abottom edge 50 which slidably engages slider 84. Sidewalls 48 extend toform ears 52, each having an aperture 54 for receiving pin 44. Apertures54 define a pivot axis 56 about which lifter 46 may pivot on pin 44. Asshown in FIG. 7, a bend 58 is formed in each sidewall 48 to orient thesidewalls so that they will not contact the interior surface of sides 38of body 12. Lifter 46 is configured with an upper dished orsaddle-shaped surface 60 as shown in FIGS. 5 and 6 for cradling acrossbar. Upper surface 60 forms a lifting surface, for engaging acrossbar, in a manner to be described, and preferably has one or moreprotruding linear teeth 62 having a length indicated at 64 as shown inFIG. 3.

As shown in FIG. 3 and 4, lever 66 is tapered and is formed with anupper arcuate surface 68 and a lower arcuate surface 70. As shown inFIGS. 5 and 6, lever 66 is formed with a pair of spaced-apart prongs 72that define a cleft or void 74. Lever 66 is formed with spacers 76 (seeFIG. 7 also) to provide clearance between lever 66 and sidewalls 48 oflifter 46. An aperture 78 is formed in spacer 76 of lever 66 to define apivot axis which corresponds to pivot axis 56 when lifter 46 and lever66 are mounted in body 12 by pin 44.

An actuator, generally indicated at 82 (see FIG. 3), is mounted in body12 and is selectively operable for simultaneously pivoting lifter 46 andlever 66 to clamp a crossbar and a rail, respectively. Actuator 82includes a slider 84 which may be a cylindrical barrel nut as shown.Slider 84 includes a first portion 84a for slidably engaging lifter 46against bottom edges 50 and a second portion 84b for slidably engagingarcuate surfaces 68 of lever 66. Slider 84 is moved inwardly oroutwardly, relative to body 12, by a tensioner in the form of a threadedbolt 86, preferably T-shaped and cylindrical, having a head 88. As shownin FIGS. 3 and 4, a handle 90 engages head 88 and is manually operablefor rotating bolt 86 about its longitudinal axis thereby to push or pullslider 84. A first locking position of handle 90 is shown incross-section in FIG. 3, and a second operating position is shown indashed lines. Handle 90 is preferably retained on bolt 86 by T-shapedhead 88, as shown best in FIGS. 3 and 4.

Handle 90 includes a semispherical bearing end 92 which mates withsemispherical receptacle 28. The semispherical shapes of end 92 andreceptacle 28 enable handle 90 to be pivoted, as shown in dashed linesin FIG. 3, and to be rotated as required to threadably extend or retractbolt 86 in slider 84. A bolt-receiving receptacle is indicated at 94,into which bolt 86 extends, and by which head 88 is retained relative tohandle 90. A latch-receiving tab is indicated at 96.

As shown in FIGS. 3 and 4, an optional accessory for tower assembly 10includes detachable pad 98, preferably a nonmarring, resilient rubberpiece shaped as shown in FIG. 4. Pad 98 includes upwardly-extendingsidewalls 100, each of which includes a cylindrical retaining post 102having an enlarged head 104. Post 102 is insertable into slot 40 tothereby anchor pad 98 to body 12. Pad 98 further includes a tongue 106(see FIG. 3) located to underlie lever 66, including an alignment ridge108 insertable into cleft 74 of lever 66, thereby maintaining tongue 106in alignment with the lever. A void-filling heel is formed in pad 98, asindicated at 110, which mates with opening 36 of bottom 30 to furtherretain pad 98 on body 12.

Another optional accessory is a lock 112, shown in FIGS. 3 and 4, whichincludes a keyed core 114 and a latch 116 that engages tab 96 of handle90, thereby locking the handle relative to body 12.

A pair of tower assemblies 10 operate to clamp a crossbar, such ascrossbar 118 shown in FIG. 1, by clamping end portions 118a and 118b toeach tower assembly body, and in turn to opposed rails R Two crossbars118 are shown in FIG. 1, with a carrier 120 mounted on one, in the formof a fork-mount bike carrier 120a and a wheel tray 120b. Crossbars 118are shown attached to a vehicle 122, with a roof indicated at 124 and afactory installed roof rack indicated at 126. Factory side rails areshown at R, on opposite sides of the roof, and factory crossbars at 130.

Clamping mechanism 42 of the present invention can be described asgenerally wedge-like, where the angle of the wedge can be adjusted tocreate outwardly directed clamping forces by means of a reverse-acting"scissors" action of lifter 46 and lever 66 to clamp a crossbar and arail simultaneously against the top of body 12 and its bottom 30,respectively. As shown in FIGS. 3 and 4, barrel nut 84 is slidablyinserted between lifter 46 and lever 66, and is retained in thatposition by bolt 86. Barrel nut 84 is pulled toward pin 44 by threadingbolt 86 into the barrel nut, and its surfaces 84a and 84b engage edges50 and surfaces 68, respectively. This action pivots lifter 46counterclockwise (as seen in FIG. 3) about pin 44 to clamp a crossbarinserted in body 12, such as crossbar 118, and at the same time pivotslever 66 in the opposite direction, clockwise, to clamp factory siderail R. Outwardly-directed clamping forces are opposed by the topinterior wall 14 of body 12 encompassing crossbar 118, and by legs 32 atbottom 30. The bottom, of course, has been inserted underneath factoryside rail R The tower assembly is thus securely fastened to bothcrossbar 118 and factory side rail R by one simple action of operatinghandle 90 to rotate bolt 86.

Lever 66 is both arcuate and tapered, and looks somewhat like the clawof a hammer. The cooperation between barrel nut 84, lever 66 and legs 32enables factory side rails R of various cross-sections and sizes to begripped with a single configuration and size of tower assembly. Lever 66and rail clamping surface 37 generally define a triangular opening orrail receiving aperture. This triangular configuration persists as thelever is pivoted down to reduce the size of the opening. The triangularshape is significant because it allows the tower to be securely mountedto rails of many different shapes by providing a tripod contact pattern.A three point contact pattern is very stable on rails of almost anycross-sectional shape and size.

Use of tower assembly 10 of the present invention avoids the need toselect a tower specifically designed for a specific vehicle, enablingone to interchangeably use the tower assembly on different vehicles anddifferent roof racks. Nonmarring rubber pad 98 is attached to the towerassembly so that lever 66 and surfaces 34 of legs 32 are covered,thereby protecting factory side rail R from damage during installationand use of the tower assembly.

In the preferred embodiment, lifter 46 has a dished or saddle-shapedupper surface 60 to engage or conform to cylindrical crossbar 118, andincludes linear teeth 62 punched to protrude slightly above that uppersurface. Teeth 62 prevent a crossbar from rotation relative to the towerassembly, thus ensuring that carriers such as fork mount 120 (shown inFIG. 1) or wheel tray 120b are maintained properly oriented for use.Upper surface 60 and the length 64 of protruding teeth 62 minimize theamount of marring through the surface of a crossbar, in addition.Alternatively, lifter 46 may be contoured to conform to other shapes ofcrossbars, such as those with square, rectangular or othercross-sections.

Installation of tower assembly 10 as above described may proceed asfollows. Initially, as shown in FIG. 1, a first tower assembly, such asthe one next to the front passenger side is placed on a factory siderail R so that its legs 32 slip under rail R. Actuator 82 is operated byturning handle 90 as if it were a screwdriver, so that lever 66 ispivoted downwardly to engage rail R and clamp it against legs 32 of body12. A crossbar, such as at 118, is then fed into the opening at the topof body 12, between the upper surface of lifter 46 and interior wall 14.Next a second tower assembly is mounted on the opposite side, adjacentthe side of the driver, with its legs slipped beneath the oppositefactory side rail R.

Crossbar 118 is then slid into the second tower assembly, until end 118aand opposite end 118b extend outwardly from each tower assembly thedesired distance. This automatically adjusts the spacing between thetower assemblies to fit a particular factory rack on which the crossbaris being mounted. Actuator 82 on each tower assembly is then furtheractuated to selectively pivot lifter 46 and lever 66 in oppositedirections so that lifter 46 securely grips crossbar 118 and lever 66securely clamps rail R against body 12. This is done by rotating handle90 to thread bolt 86 into barrel nut 84, thereby pulling the barrel nutagainst lifter 46 and lever 66. It should be appreciated that the towerassemblies are interchangeable, meaning that they can be used as shownin FIG. 1, with each rear wall 18 oriented to face outwardly, by simplyturning each tower assembly appropriately. Alternatively, rear wall 18of one or more of the tower assemblies could be oriented to face towardthe inside of the rack, if desired.

The tower assembly of the present invention provides several distinctand important advantages. First, the unitary construction of body 12 andthe generally C-shaped profile with opening 36 permit tower assembly 10to be easily mounted on a rail, such as a factory-installed rail shownin FIG. 1. Initially, actuator handle 90 is operated so that secondlever 66 is opened to permit sufficient room for a rail to be insertedbelow the lever and above bottom 30. With the tower assembly sopositioned, a crossbar may be fed in from the right (viewing FIG. 3) sothat it extends through aperture 20 on top 13 of body 12 as shown. Asecond tower assembly is then mounted on the opposite rail and thecrossbar is then fed through the top of the body of that tower assembly.Depending on the desired ultimate positioning of the tower assembliesand the relative position of a crossbar, the tower assemblies may belongitudinally shifted along the rails and the crossbar may be laterallyshifted to a desired position. Once that is accomplished, the actuatorhandles of the respective tower assemblies are manipulated to draw orpull slider 84 to effect the clamping action of lifter 46 against thecrossbar and second lever 66 against the rail. Additional towerassemblies and crossbars may be mounted as desired.

The tower assembly of the present invention is a compact, integral unit,and the mounting of pivot pin 44, to provide a common pivot axis forlifter 46 and second lever 66, facilitates the compactness of the unit.By mounting pivot pin 44 as shown, a region, such as indicated at 36 inFIG. 3, is provided enabling a rail to be quickly positioned beneathsecond lever 66 and above bottom 30. Tower assembly 10 of the presentinvention is dimensioned so that it may be readily handled. Moreover,handle 90 enables one to quickly adjust the clamping forces on acrossbar and rail, thereby enabling quick mounting or detachment of thetower assembly.

Provision of a common pivot axis for lifter 46 and second lever 66enables the lifter and second lever to pivot in opposite directionsthereby providing simultaneous clamping of a crossbar and a rail to body12. A person needs to make only a single adjustment to effect completeclamping. By adjusting the bolt, the clamping assembly is adjustableover its full range of travel to grip rails of various sizes andcross-sections. By providing the arcuate surface such as indicated at 68on second lever 66, slider 84 may travel smoothly therealong, duringclamping action, while still exerting a force upwardly against edges 50of lifter 46. Still further, by providing the C-shaped profile, asdescribed above, and the region indicated at 36, sufficient room isprovided to position a protective pad such as indicated at 98.

With the unitary construction as described and the recesses describedwith respect to inclined rear wall 18, handle 90 is mounted so that whenit is in its nonoperative position, the profile of the back wall and thehandle visually blend, again providing a relatively compactconfiguration. The unitary body houses the components for the clampingaction and provides an upper region for receiving a crossbar and a lowerregion for a rail.

An alternative embodiment of a clamping assembly 200 according to thepresent invention is shown in FIGS. 11-14. In particular, clampingassembly 200 utilizes a monolithic or unitary wedge-like cam 202 inplace of first and second levers 46, 66 and slider 84. Cam 202 includesa transverse cylindrical aperture 204 adapted to receive a barrel nut206, similar to slider 84. Threaded bolt 86 is engaged in barrel nut 206to selectively pull or draw the cam toward tower body 12, therebyactivating or operating the clamping assembly.

Cam 202 includes a lower rail contacting surface 210 and an uppercrossbar contacting surface 212. In the preferred embodiment, thecrossbar contacting surface is generally somewhat concave to conform tothe round surface of the crossbar and includes plural longitudinalridges 214 to prevent the crossbar from rotating when secured in thetower. The crossbar contacting surface is bisected by a channel 216 intowhich the portion of the bolt extending through the barrel nut extends.The channel has a bottom which engages the projecting portion of thebolt to limit the upward pivotal motion of the cam about the barrel nut.

It is necessary to limit the pivotal motion of the cam to cause the camto be pulled upward against the crossbar when the rail contactingsurface engages the rail. If the pivotal motion were not limited, thecam could simply continue to rotate as it was drawn back toward the bodyand would not be firmly urged upward against the crossbar.Alternatively, a portion of the cam could project laterally into a pairof the channels formed on the inside surfaces of the tower body andextending generally parallel to the bolt axis to guide the cam in alinear path while still allowing it to pivot as the cam is pulled backby the bolt. In either case, the basic requirement is that an upwardtorque be created on the cam when the rail contacting surface engagesthe rail to thereby simultaneously clamp both the rail and the crossbar.

One of the benefits of either of the above-described embodiments is thatthe clamping assembly and tower body are pre-assembled as a single unitfor the user, and all the pieces of the clamping assembly remain fixedto the tower body during installation and removal. Thus, the tower bodyand clamping assembly remain operatively connected in a single unit asthe rail receiving passage is varied between its minimum and maximumsizes. This eliminates the need for a user to assemble any pieces of thetower prior to attachment to the rail or crossbar. In addition, bothembodiments are continuously variable over their range of operation bysimple turning of the actuator bolt. This is in contrast to some deviceswhere a piece must be disconnected and reattached at a differentlocation to allow the full range of adjustment. The present inventionthus simplifies operation and eliminates the chance of lost pieces thatarises when separable parts are used.

While the present invention has been shown and described with referenceto the foregoing preferred embodiments, it is to be understood by thoseskilled in the art that other changes in form and detail may be madewithout departing from the spirit and scope of the invention as definedin the appended claims.

I claim:
 1. A tower assembly for detachably mounting a transverselyextending crossbar to a longitudinally extending rail of avehicle-mounted roof rack comprising:a tower body including a railclamping surface against which a rail is to be clamped and a crossbarclamping surface against which a crossbar is to be clamped; a clampingassembly coupled to the tower body and configured, upon operation, tourge the crossbar against the crossbar clamping surface andsimultaneously to, through reactive force resulting from urging thecrossbar against the crossbar clamping surface, urge the rail againstthe rail clamping surface, wherein the two clamping surfaces aredisposed generally opposite one another and the clamping assembly isconfigured to urge the rail and the crossbar generally apart from oneanother and against their corresponding clamping surfaces; and a railreceiving passage into which the rail is to be installed, the railreceiving passage being bounded at least in part by the clampingassembly and the rail clamping surface, the clamping assembly beingconfigured to substantially and selectively vary the size of the railreceiving passage to accommodate clamping rails of various sizes andcross sections in the rail receiving passage.
 2. The tower assembly ofclaim 1, wherein the size of the rail receiving passage is variablebetween a predetermined minimum size and maximum size and the tower bodyand clamping assembly remain operatively connected in a single unit asthe rail receiving passage is varied between the minimum size andmaximum size.
 3. The tower assembly of claim 1, wherein the clampingassembly and tower body are pre-assembled to form a single unit which ismaintained as a single unit during normal operation.
 4. The towerassembly of claim 1, wherein the clamping assembly includes a generallywedge-shaped portion.
 5. The tower assembly of claim 4, wherein thewedge-shaped portion is monolithic.
 6. The tower assembly of claim 5,wherein there is a space between the rail and the crossbar when they aremounted in the tower body, and the wedge-shaped portion is drawn intothis space upon operation of the clamping assembly.
 7. The towerassembly of claim 4, wherein the wedge-shaped portion includes upper andlower levers pivotally connected to the tower body for pivotal motionabout a first pivot axis and the two levers are spread away from oneanother upon operation of the clamping assembly.
 8. The tower assemblyof claim 7, wherein the clamping assembly includes a slider disposedbetween the two levers, where the slider is drawn toward the first pivotaxis upon operation of the clamping assembly.
 9. A tower assembly fordetachably mounting a transversely extending crossbar to alongitudinally extending rail of a vehicle-mounted roof rackcomprising:a tower body configured to receive the rail and the crossbarand including a rail clamping surface against which the rail is to beclamped and a crossbar clamping surface against which the crossbar is tobe clamped, with the clamping surfaces being generally opposed to eachother and the rail clamping surface including a fixed lower surface andan adjoining fixed side wall, the tower body further including a lateralrail opening communicating to the rail clamping surface to allow thetower body to be slipped on and off the rail in a direction generallyradial to an elongate axis of the rail; a clamping assembly coupled tothe tower body and configured, upon operation, to urge the crossbaragainst the crossbar clamping surface and simultaneously to, throughreactive force resulting from urging the crossbar against the crossbarclamping surface, urge the rail against the lower surface and side wallof the rail clamping surface.
 10. The tower assembly of claim 9, whereinthe tower body and clamping assembly remain operatively connected in asingle unit as the tower body is slipped on and off the rail and theclamping assembly is operated.
 11. The tower assembly of claim 9,wherein the clamping assembly at least partially closes the lateral railopening upon operation of the clamping assembly.
 12. The tower assemblyof claim 11, wherein the clamping assembly and tower body adjacent therail clamping surface define a rail receiving passage having a generallytriangular cross-section.
 13. The tower assembly of claim 12, whereinthe clamping assembly is continuously adjustable to vary the size of therail passage are a substantial range to accommodate rails of varioussizes and cross-sections.
 14. The tower assembly of claim 13, whereinthe clamping assembly includes a generally wedge-shaped portion formingone wall of the rail receiving passage.
 15. A tower assembly fordetachably mounting a transversely extending crossbar of predeterminedcross-section to a longitudinally extending rail on a vehicle-mountedroof rack, the tower assembly comprising:a tower body for receiving aportion of the crossbar and an adjacent transversely oriented portion ofa rail, the tower body being adapted to constrain the movement of therail and the bar away from one another. a selectively operable clampingmechanism housed in the tower body and including a wedge-shaped portionadapted to be disposed generally between the rail and the crossbar whenthe rail and the crossbar are received in the tower body, the clampingmechanism further being configured, upon operation, to urge the bar andthe rail away from each other and against the tower body to therebysecure the bar and the rail to the tower simultaneously.
 16. The towerassembly of claim 15, wherein the wedge-shaped portion is monolithic andis adapted to be shifted in between the crossbar and the rail uponoperation of the clamping mechanism.
 17. The tower assembly of claim 15,wherein the clamping mechanism includes an actuator, where the actuatorincludes a bolt which engages the wedge-shaped portion to selectivelyshift the wedge-like portion.
 18. The tower assembly of claim 15,wherein the wedge-shaped portion includes pivotally mounted upper andlower levers that are forced apart from one another upon operation ofthe clamping mechanism.
 19. The tower assembly of claim 15, wherein theupper and lower levers are pivotally mounted about a common pivot axisand are forced apart by a slider adapted to be disposed between thelever and drawn toward the pivot axis upon operation of the clampingmechanism.